Ectomycorrhizae of Young and Mature Scots Pine Trees in Industrial Regions in Poland

Ectomycorrhizae are obligate symbiotic structures of forest tree roots and are susceptible to environmental changes. Ectomycorrhizae of Scots pine (Pinus sylvestris L.) trees grown in forests influenced by different levels of air pollutants were investigated. Total numbers of mycorrhizal root tips in the soil horizons and the frequency of mycorrhizal morphotypes were studied as indicators of ectomycorrhizal status. The studies were conducted in two comparable young plantations in western Poland with high and low pollution exposure and in two mature forest ecosystems in southern Poland differing in pollution exposure. At the young Scots pine plantation with high pollution exposure (Luboń), numbers of mycorrhizal root tips in the soil layer 0–5 cm were lower during three growing seasons than at the cleaner site (Kórnik). In the soil layer 15–30 cm the total number of mycorrhizal root tips was found slightly higher at the polluted than at the control site. There was no difference in the frequency of the seven mycorrhizal morphotypes found at the two young plantations. At the heavily polluted mature forest stand (Niepołomice Forest) the total number of mycorrhizal root tips was lower in zones of severe pollution levels than in the less polluted zones. Moreover, the average number of mycorrhizae in the Niepołomice Forest was lower than in the moderately polluted forest ecosystem (Ratanica catchment). The mycorrhizal diversity of the mature pines in the heavily polluted forest was reduced (four morphotypes) as compared to the moderately polluted forest (eight morphotypes). The relationship between industrial pollution and mycorrhizal status was more pronounced at the mature Scots pine stands than at the young plantations.